The most diverse methods for determining at least one physical parameter by means of a sensor unit are known from the prior art. These measurement methods frequently have in common a dependence on temperature, which is explained below with reference to inductive and capacitive measuring systems, provided the physical measured value is converted to an electrical value.
WO 2012/104086 A1 discloses a method for locating metal or metal-containing objects and materials, this method controlling currents in at least two transmitting coils in relation to one another such that a received signal that is received by at least one receiving coil, or mean values of demodulation phases generated from the received signal, are continuously controlled in relation to one another to give a zero value even when influenced by metal. In this case, the control values are detected as values at least at 0° and 90° and are taken into account in the calculation thereof such that an exact analysis of the metal objects located in the detection region is achieved. With this method, although a metal object can be analyzed, movements of the object in a particular direction of measurement cannot be unambiguously recognized. German patent application DE 10 2012 001 202 A1 describes a sensor comprising a coil arrangement in which the normally circular windings of a coil are configured in a meandering shape. Two transmitting coils and one receiving coil cooperate such that the received signal becomes zero. In this case, a respective transmitting coil is preferably arranged above and below the receiving coil. These transmitting coils have angles of rotation that are slightly different from the receiving coil, so by way of the distribution of transmitted currents the signal in the receiving coil can be controlled to give a zero value.